Earthed

What can be determined about an extrasolar planet observed from Earth?

Just curious what can specifics be determined about extrasolar planet from Earth?



Specifics I am thinking might concern is a planet's rotation, size, climate and habitability, etc.



Also, how far would a high-end, home-telescope reach in terms of observing a planet? How many light years, etc.?



Please only reply if you know! I'm not looking for guesses ;-)



Thanks much!

Public Comments

1. Approx size and chemical makeup can be determined along with its revolutions around its nearest star. I have no idea about distance of a home telescope but I doubt you could see a planet outside this solar system unless it was huge.
2. There are no home-telescopes that can directly observe planets around other stars. The ones that can detect planets are huge. Most extra solar planets are detected indirectly by observing a very slight wobble in a star caused by the gravity of the star and planet interacting with each other. Astronomers can approxomate the mass and orbit of the planet, and make guesses about what the surface temperature might be based on how close it is to the star.
   
   
   
   In some systems the planet passes directly between the distant star and us, so astronomers are able to detect a slight change in brightness as the planet transits the star. This allows them to estimate the density of the planet because they can also see how big it is by looking at how much light from the star it blocked.
   
   
   
   I know that astronomers have been trying to determine the composition of the atmosphere by doing a spectral analysis of the light from the star as the planet transits, but I'm not sure if this has been done successfully.